Geologic Map of the Carlsbad Caverns 7.5-Minute Quadrangle
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NEW MEXICO BUREAU OF GEOLOGY AND MINERAL RESOURCES A RESEARCH DIVISION OF NEW MEXICO INSTITUTE OF MINING AND TECHNOLOGY NMBGMR Open-File Geologic Map 285 Last Modified June 2020 Correlation of Map Units Description of Map Units 104°30'0"W 104°27'30"W 104°25'0"W 104°22'30"W 490000 548000 549000 550000 500000 551000 552000 553000 510000 554000 A 555000 556000 520000 557000 558000 QUATERNARY PERMIAN Capitan Formation 32°15'0"N Py Qy 32°15'0"N Qy Py Qyc Capitan Formation—From a distance this unit exhibits a weekly Qy Py Qy Holocene Ochoan Pcp Pt Py Qyc Qy Py Holo. developed inclined layering that dips southeastward between ~15° and 000 Holocene Sedimentary Deposits Castile Formation Alluvial Alluvial Deposits 3568 Pt Qy Deposits Holocene 4 Holocene Psr Qyc Qyc 000 3568000 30°. This layering is more pronounced closer to the Delaware basin. In Qy Qy Pt Qy 0 Active channel deposits—Predominantly unconsolidated sand and Castile Formation—Composed of alternating regular laminae and thin Py 0 Qyc Pc Qy Pt 0 Qs outcrop, most exposures appear massive and structureless. A faint Qy 4 0 gravel dominated by clasts of carbonate surrounded by a silty to sandy beds of dark-colored and light- colored anhydrite. Layering is mostly 0 e Pt e Qy Psr 8 Qy 02 3 brecciated texture is visible locally where angular clasts of dolomite of n n carbonaceous matrix. Mostly devoid of vegetation though some low contorted and is rarely consistent for more than a few meters. Both 04 03 01 Qyc e 05 04 03 e Qss e e Pt c Py c terraces typically less than 1 m above the active channel contain weak stream-cut exposures and upper surface exposures show abundant all sizes are strongly cemented by different generations of carbonate. n 06 n o Qy o t t e Py e Coarse-grained light yellow palisade calcite spar commonly fills s c s c Qsl Features soil horizons and thicker vegetation. Thickness unknown but probably brittle deformation cracks, many of which on the surface are filled with i 00 Qy i 0 Qy Dissolution o 4 Qy o e Qy e l l l Pt l less than several meters. fine sediment. As mapped, many areas underlain by anhydrite are dissolution fissures and cracks. Fossils of sponge and brachiopod o Qy o Qyc Qyc P Psr Py Qy P Qsc H H fragments are locally visible. Forms steep slopes and imposing cliffs. d d extensively mantled by a thin layer of alluvial and eolian deposits a 0 n 0 n 38 This unit represents the fragmented debris shed from the ancient reef a a Ql Older Holocene sedimentary deposits—These deposits are composed few cm thick. Low widely spaced dunes are visible on some of these Qy Qy Qy 3567000 Py down into the Delaware basin. 000 of weakly to strongly indurated sand and gravel in a silty to sandy surfaces. 3567 Quaternary Older Older Alluvial Qm Alluvial Deposits Qy Pt Deposits 450000 Qy 450000 carbonaceous matrix. They form terraces typically between 1–3 meters Py Qy Bell Canyon Formation Py QTc2 above the active channel deposits. Most terraces have well developed Guadalupian Quaternary Fine-grained sandstone/siltstone member of the Bell Canyon and Tertiary silty soil that supports abundant vegetation, particularly grasses. Artesia Group Pbcs Pt QTc1 Deposits Qy Pt Formation—Thin-bedded to laminated planar beds of siltstone and Pt Sedimentary Estimated thickness up to 5 meters. This group probably contains the Tansill Formation, the Yates Formation, and Ql fine-grained sandstone. Typically erodes into smooth slopes. Fresh Qy the Seven Rivers Formation, but the merging and pinch-out of these formations Py Qy 10 surfaces are commonly light-mustard yellow in color. 09 10 11 12 Pt 09 against the Capitan Formation does not allow for these units to be easily 07 08 Qy Castile Holocene and Pleistocene Ochoan Pc Formation Dissolution Features distinguished from one another. The Artesia Group here forms the well bedded 3566000 Qy 4 00 Tansill Queen and Grayburg Formations, undivided 0 3566000 Pt Sinkholes—Most of these features form shallow depressions filled dolomite and interbedded siltstone/fine- grained sandstone layers that overlie n Formation n Qs n o o a a Queen and Grayburg Formations, undivided—Queen and Grayburg o p p i Qy i y 0 y 0 i Pqg 0 t s Py s n Pt n with fine-grained silt and clay that supports the growth of grasses and the Capitan Formation. The siliciclastic layers thin and pinch out to the u 4 u Yates a a a e e o o t Py t Pcp Pbcs Formations, undivided. This unit is present in the cross section only. C C m r Qy r r r Formation r l Py l other vegetation. Most of these features are sub-circular are range from southeast against the Capitan Formation. Bedding merges gradually with the Capitan l l Pt o G G e e Formation A Qy A F B Pt Seven Rivers B Qy Pt Psr several meters across to tens of meters across. The majority of these underlying massive Capitan Formation. Fossils are rare. Beds locally show faint Qsl Qy Formation Qsl Goat Seep Formation Permian QTc1 QTc2 Queen and Goat Seep Cherry features occur in the older sedimentary deposits ( and ) that subhorizontal fenestrae that may have been originated as algal matts. Locally Guadalupian Pqg Grayburg Pgs Pcc Canyon Goat Seep Formation—Upper unit; mostly limestone, in part 4000 Formation overlie the anyhydrite of the Castile Formation (Pc) where they contains thin beds of pisoliths. Pgs Qy Qy Frms. Formation dolomitic, in part sandy, mostly thick bedded, massive, light gray to Qy Qyc Bone Springs probably represent the surface expression of collapsed dissolved Pbs Formation Qy Leonardian brownish yellow; sandstone interbeds more abundant downward; Psr Qy Qy Qy caverns that have filled with sediment. Tansill Formation Qy 3565000 poorly preserved marine fossils; thickness is from 200+ to 1,200 ft. 000 Tansill Formation—Mostly light gray dolomite and minor thin dark Py 3565 Pt Lower unit; mostly sandstone, very fine to fine grained, soft, brownish Qy Pt Disappearing streams—These features are near-vertical caverns in the tan siltstone beds. Dolomite beds are mostly thick-bedded and massive Qss yellow to pink; sone units of limestone, cherty, sandy, thin bedded, Psr Qy Qy Py anhydrite of the Castile Formation (Pc) into which local streams drain though locally faint layering within beds is defined by sub-horizontal 15 Qy 14 Qy Qy Qy brown, limestone more abundant in Guadalupe Mtns; forms moderate 16 13 Qy Qy 17 16 15 and disappear without apparent external drainage locations. fenestrae. No fossils are obvious. The lower portion of this unit forms a Qy slope; silicifed marine fossils; thickness is from 150 to 300 ft. This unit Qy Qy Qy Pt 0 18 20 prominent cliff that overlies the uppermost slope-forming thick Qy 4 is present in the cross section only. Qy Qy Externally drained collapse features—These few features are larger siltstone layer of the underlying Yates Formation. Close to the reef front Qy Ql Py Qsl than unit Qs. They are circular in shape and form depressions that (unit Pcp) the unit contains some teepee structures, but fewer than in Cherry Canyon Formation Qy 4000 have been breached by external drainage. These features are typically the immediately underlying Yates Formation. Some beds contain Qy Cherry Canyon Formation—Sandstone, siltstone, and limestone. 3564000 much deeper than the smaller sinkhole depressions of Qs and are abundant pisoids (or pisoliths), but overall pisoids are less abundant in Pcc 3564000 Mostly very fine-grained quartz sandstone and siltstone, mostly found in the southeast corner of the map within unit QTc2 and in the the Tansill Formation in the quadrangle than within the Yates noncalcareous, in part shaly, mostly thin bedded, some varvelike 440000 440000 Pt northern portion of the map within dolomite. Formation. Pt bedding and ripple marks, irregularly bedded channel fillings 32°12'30"N 32°12'30"N T024ST024SR024ER024E T024S R025E T024S T024S R025E T024S common in lower two-thirds. Locally persistent thin quartzite beds in Qy Cave—Only one feature contains this map label—the opening to Yates Formation Qsc lower part. Sandy limestone in thin beds, lenses, and nodules in a few Qy Carlsbad Caverns. It was given its own map label because of its size Yates Formation—Interbedded dolomite and siltstone/fine-grained Qsl Py places. Limestone, thin to thick bedded, some sandstone interbeds. Pt 4200 and significance. sandstone. Characteristically contains many more interbeds of dark Qy Western Apache Mountains; interbedded dolomite, limestone, and fine Pt yellow-weathering siltstone and fine-grained sandstone than does the 4 to very fine-grained dolomitic sandstone; basal 50 ft. exposed. 6 22 000 21 0 23 24 Older Alluvial Deposits overlying Tansill Formation. Dolomite is typically massive and 3563 0 19 20 21 22 000 Thickness 1,000 ft. This unit is present in the cross section only. 3563 Late Pleistocene sedimentary deposits—Contains poorly sorted, fenestrate, and commonly weathers a dark tan color compared to the Pt Ql Pt angular to subrounded material from boulders to sand and silt lighter gray weathering of the Tansill Formation. In Walnut Canyon the Py Qy Leonardian 0 Explanation of Map Symbols composed dominantly of dolomite locally derived from the nearby unit contains abundant beds of pisoids (or pisoliths) interbedded with Py 46 0 Bone Spring Formation Qy Py Pt bedrock and strongly cemented by carbonate. This unit forms small dolomite.